The process of 3D modeling is actually a mathematical component one needs to develop in order to represent the surface of the object as a complete image. A model could be created using a computer program or by hand. Models created by hand are not very common nowadays; most designers prefer to work with a computer screen and keyboard to create prototypes.
The models generated on a computer screen use a geometric equation connecting points or triangles, curves, lines and so on. These geometric equations can be created by hand on paper with the same collection of data points used in the computer rendering. Then they can be scanned into a computer for further manipulation.
There are many different computer software programs available for individuals who want to manipulate a photo rendering for more dimensions. These various programs allow the user to add and subtract depth and do the same for mesh. They can also stretch various aspects of a photo's components. All of this gives a photo a life-like look.
If the metadata is compatible with other files, the person manipulating the photo can import other pieces of data into their photo to create more depth. There are many different techniques someone can integrate into a photo to make it seem real. The person doing the modeling can also map different textures into their photo to give it an even more real feel.
There are two types of representations with this type of models, solid and shell/boundary. The solid is like a rock, it will define the volume of the object you want to represent. They are a little more difficult to draw because they are more realistic in nature. This type of model, the solid model is used in engineering and medical simulated drawings to help doctors and city planners understand better what they need to do.
The shell/boundary types of models or drawings represent the boundary or surface of the object. This is the type of model or drawing that is used in video games. It is much easier to work with as a model and easier to draw for both beginners and experienced modelers.
In computer graphics, boundary representations are the most common because of their appearance. The surface of the item needs to be what is represented most. This is because the exterior of the item you are representing is what is seen, however the interior is what gives the item its depth. All of these needs to come together and that is why you need the complex mathematical equations.
To bring everything together, many modelers use meshing. Instead of meshing squares or circles, they tend to mesh together triangles. Meshing together triangles is a popular way to render a scene from the abstract to something life-like for 3D modeling. This meshing of triangles can be done on paper or with a computer program with wonderful, multilevel results.